Sustainable approach to synthesis of carbon Dot/ silver nanoparticles for biological evaluation as antimicrobial agent

Abstract

Abstract Green synthesis of metal nanoparticles is an attractive substitute for traditional methods using capping and reducing chemicals. In this study, silver nanoparticles (AgNPs) were synthesised using carbon dots (CDs) derived from bioresources as reducing, protecting, and stabilising agents in a single step using environmentally friendly and cost-effective synthetic methods. The optical and structural properties of prepared CD/AgNPs were explored using UV–vis (Ultraviolet-Visible Spectroscopy), Fluorescence spectroscopy, XRD (x-ray Diffraction), DLS (Dynamic Light Scattering), SEM-EDX (Scanning Electron Microscopy with Energy-Dispersive x-ray Spectroscopy) and TEM (Transmission Electron Microscopy). The synthesised CD/AgNPs are stable as zeta potential value is −14.7mV. From TEM the particle size exhibited as ∼12 nm. The prepared CD/AgNPs exhibited significant optical absorbance, good water dispersibility, stability and nano size. Also, CD/AgNPs revealed good biocidal effects against Gram-negative bacteria Escherichia coli (E. coli), Pseudomonas Aeruginosa (P. aeruginosa), Gram-positive Staphylococcus Aureus (S. aureus), Bacillus Cereus (B. cereus), and good anti-fungal activity against Aspergillus Niger (A. niger). The CD/AgNPs were further analyzed by live/dead assay. E. coli and A. niger with zone of inhibition around 3.1 and 40 mm, respectively when compared to ciprofloxacin (2.2 mm) and fluconazole (25 mm). The above investigation proved that the developed CD/AgNPs will be a new platform as an alternative to the traditional antibiotics for the generation of new kind of antibacterial materials and also provide the pathway for various metal/CD nanomaterials for diverse biomedical applications.